My idiosyncrasies: deferred subject in Latin = deferred subject in English; always use “lest” for ne, even when it introduces a negative wish. Remember, they are singing. I’m less constrained to go for prose sense.
“Dominus illuminatio” (Psalm 26)
 Psalmus David, priusquam liniretur. Dominus illuminatio mea et salus mea; quem timebo? Dominus protector vitae meae; a quo trepidabo?
A Psalm of David, before he would be annointed. The Lord my light and my safety; whom shall I fear? The Lord, the protector of my life; from whom shall I tremble?
 Dum appropiant super me nocentes, ut edant carnes meas, qui tribulant me inimici mei, ipsi infirmati sunt et ceciderunt.
When they draw near over me, the harmers, that they may eat my flesh, who trouble me, my enemies, they have been weakened and fallen.
 Si consistant adversum me castra, non timebit cor meum. Si exsurgat adversum me praelium, in hoc ego sperabo.
Should they stand against me, the camps, my heart shall not fear. Should it rise against me, the battle, in this I myself shall hope.
 Unam petii a Domino, hanc requiram, ut inhabitem in domo Domini omnibus diebus vitae meae, ut videam voluptatem Domini, et visitem templum ejus.
One have I sought of the Lord, this shall I seek, that I may dwell in the house of the Lord all the days of my life, that I may see the delight of the Lord and visit His temple.
 Quoniam abscondit me in tabernaculo suo; in die malorum protexit me in abscondito tabernaculi sui.
For He hath hidden me in His tabernacle; in the day of evils He hath protected me in His hidden tabernacle.
 In petra exaltavit me, et nunc exaltavit caput meum super inimicos meos. Circuivi, et immolavi in tabernaculo ejus hostiam vociferationis; cantabo, et psalmum dicam Domino.
On the rock He has exalted me, and now He has exalted my head over my enemies. I have gone about and have immolated in His tabernacle a victim of shouting; I shall sing, and speak psalm to the Lord.
 Exaudi, Domine, vocem meam, qua clamavi ad te; miserere mei, et exaudi me.
Hear, O Lord, my voice with which I have cried to Thee; have mercy on me and hear me.
 Tibi dixit cor meum, exquisivit te facies mea; faciem tuam, Domine, requiram.
To Thee has spoken my heart, it has sought Thee, my face; Thy face, O Lord, shall I seek.
 Ne avertas faciem tuam a me; ne declines in ira a servo tuo. Adjutor meus esto; ne derelinquas me, neque despicias me, Deus salutaris meus.
Lest You turn Thy face from me; lest You bend down in wrath from Thy servant. Be Thou my helper; lest You abandon me, lest you despise me, O God my Savior.
 Quoniam pater meus et mater mea dereliquerunt me; Dominus autem assumpsit me.
For my father and my mother have abandoned me; while the Lord has gathered me.
 Legem pone mihi, Domine, in via tua, et dirige me in semitam rectam, propter inimicos meos.
Set a law for me, O Lord, in Your way, and direct me in the right path, on account of my enemies.
 Ne tradideris me in animas tribulantium me, quoniam insurrexerunt in me testes iniqui, et mentita est iniquitas sibi.
Lest you hand me over into the souls of those troubling me, for they have risen against me, unjust witnesses, and lying injustice is theirs.
 Credo videre bona Domini in terra viventium.
I believe to see the good things of the Lord in the land of the living.
 Expecta Dominum, viriliter age, et confortetur cor tuum, et sustine Dominum.
Be on the lookout for the Lord, manfully act, and let your heart be comforted, and await the Lord.
I was tempted to make liniretur “chrismated” or something more obviously messianic, but I decided not to get carried away. Then again the Septuagint does give christhenai…
Unam and hanc (v. 4) are imitating the Septuagint’s mian and tauten. Staying inside the Latin, it is tempting to assume those feminine forms are modifying a hidden petitionem or precem, but even more expected would be neuter forms corresponding with the gerund-y ut clauses. But I take what is given!
omnibus diebus? OMNIBUS DIEBUS?? I could bend over backward explaining why this is somehow subtler different than the more normal accusative of extent of time, but I’m pretty sure he’s just doing something weird here.